Trends of Mycobacterium tuberculosis and Rifampicin resistance in Northwest Ethiopia: Xpert® MTB/RIF assay results from 2015 to 2021

BACKGROUND

Tuberculosis (TB) remains one of the leading causes of morbidity and mortality worldwide, particularly in countries with limited resources. The emergence of drug resistance in mycobacterium tuberculosis (MTB), particularly rifampicin (RIF) resistance, hindered TB control efforts. Continuous surveillance and regular monitoring of drug-resistant TB, including rifampicin resistance (RR), are required for effective TB intervention strategies and prevention and control measures.

OBJECTIVE

Determine the trend of TB and RR-TB among presumptive TB patients in Northwest Ethiopia.

METHOD

A retrospective study was conducted at the University of Gondar Comprehensive Specialized Hospital (UoG-CSH). The study included TB registration logbook data from all patients who visited the hospital and were tested for MTB using the Xpert® MTB/RIF assay between 2015 and 2021. The SPSS version 26 software was used to enter, clean, and analyze the laboratory-based data.

RESULTS

A total of 18,787 patient results were included, with 93.8% (17,615/18787) of them being successful, meaning they were not invalid, error, or aborted. About 10.5% (1846/17615) of the 17,615 results were MTB-positive, with 7.42% (137/1846) RIF resistant. Age, anti-TB treatment history, and diagnosis year were associated with the presence of MTB and RR-MTB. Tuberculosis (TB) prevalence was higher in productive age groups, whereas RR-TB prevalence was higher in the elderly. Regarding diagnosis year, the prevalence of TB and RR-TB showed a declining trend as the year progressed. While MTB was detected in 12.8% (471/3669) of new and 22.2% (151/679) of re-treatment presumptive TB patients, RR-MTB was detected in 8.5% (40/471) of new and 18.5% (28/151) of re-treatment TB cases.

CONCLUSION

The prevalence of TB and RR-TB in the study area showed a declining trend over the years. While TB was more prevalent in productive age groups (15 to 45 years), RR-TB was more prevalent in older populations (over 45 years), than others. Moreover, patients with a history of anti-TB drug exposure were more likely to be positive for DR-TB, highlighting the need to strengthen DOT programs for proper management of TB treatment.

Prevalence of Methicillin-ResistantStaphylococcus aureus and Multidrug-Resistant Strains from Patients Attending the Referral Hospitals of Amhara Regional State, Ethiopia

Background

Staphylococcus aureus (S. aureus) causes different types of human infections and can develop resistance to many antibiotics. There is a scarcity of data on the mecA gene and multidrug-resistant (MDR) strain distribution of this organism in developing countries, such as Ethiopia. This study investigated the presence of mecA gene and MDR profile of S. aureus among patients attending referral hospitals of Amhara regional state.

Methods

Of the total of 110 isolates collected from Amhara regional referral hospitals, 70 MDR isolates were further processed for isolation of S. aureus mecA gene. Genomic DNA was isolated using a Sigma-Aldrich genomic DNA isolation kit for Gram-positive bacteria. Amplification of S. aureus mecA gene was performed with the amplicon size of 533 bp. Antimicrobial susceptibility test including methicillin resistance was determined by the Kirby-Bauer disc diffusion method.

Results

The majority of the isolates were recovered from patients aged less than 5 years (51; 36.7%) and the least number of isolates was recorded in age group greater than 60 years (6; 4.3%). Most of the isolates were from blood (61; 43.9%), followed by wounds (45; 32.4%). A high resistance rate was observed in penicillin (81; 73.6%), followed by cotrimoxazole (78; 70.9%), ceftriaxone (76; 69%), erythromycin (66; 60%), and tetracycline (65; 59.1%). Phenotypically, considering cefoxitin as a surrogate marker, 38 (34.5%) of the isolates were methicillin-resistant. The overall MDR isolates were 80 (72.7%). The PCR amplification result of the mecA gene was 14 (20%). Conclusions and Recommendations. High rates of MDR and methicillin-resistantS. aureus were reported. PCR amplification indicated that 20% of MRSA isolates were the mecA gene carriers. Large-scale studies for the detection of MDR strains of S. aureus including MRSA using molecular techniques should be encouraged in the Amhara region.

Potential drivers of leprosy infection: A case–control study of parasitic coinfection and water, sanitation, and hygiene in North Gondar, Ethiopia

Background

Despite extensive control measures and a declining number of human reservoirs, the incidence of leprosy in excess of 200,000 new cases each year suggests that alternative pathways of transmission may play a role in continued endemicity. Parasitic coinfection and limited water, sanitation, and hygiene (WASH) have been suggested to predispose individuals to Mycobacterium leprae infection and were further explored in this study.

Methods

Leprosy cases and uninfected controls were recruited from areas around North Gondar, Ethiopia throughout 2019. Participants completed dietary and WASH surveys in addition to providing stool for helminth microscopic diagnosis and urine for Schistosoma mansoni Point-of-care circulating cathodic antigen (POC-CCA)™ rapid diagnostic testing. A similar methodology was employed for a case–control study of leprosy previously conducted by our research team in North Gondar from May to October of 2018. To more comprehensively evaluate associations between the above exposures and leprosy, data from the present 2019 study and the previous 2018 study were combined in select multivariate logistic regression analyses.

Results

A total of 47 men (59%) and 33 women (41%) participated in this study with an average age of 40 (SD 15.0 years). Most leprosy cases were multibacillary (93%). There was a high prevalence of parasitic coinfection among both cases (71%) and controls (60%). WASH insecurities were also widespread. On multivariate analysis, lack of soap for handwashing [aOR= 2.53, 95% CI (1.17, 5.47)] and the lack of toilet facilities [Adjusted odds ratio (aOR)= 2.32, 95% CI (1.05, 5.12)] were significantly associated with leprosy. Positive directionality was identified for a number of other inputs, including helminth infection [aOR= 3.23, 95% CI (0.85, 12.35)].

Conclusions

Taken together, these findings strengthen previous research conducted in 2018 implicating poor WASH conditions as a driver of leprosy infection. Leprosy remains the leading infectious cause of disability in the world. As such, future research should explore the above susceptibilities in more depth to curtail the global burden of disease.

Bacterial Bloodstream Infections and their Antimicrobial Susceptibility Patterns in Children and Adults in Ethiopia: a 6-Year Retrospective Study

BACKGROUND

In sub-Saharan Africa, bacterial bloodstream infection is the most common cause of morbidity and mortality. Regular antimicrobial surveillance is required to understand resistance development and to inform clinicians and policymakers on best empiric antibiotic choice, such type of data are scarce in the study area. This study aimed to determine bacterial profiles and their antibiotic susceptibility patterns from patients with suspected septicemia at the University of Gondar comprehensive specialized hospital, northwest Ethiopia, over a six-year period.

METHODS

We carried out a six-year (January 2, 2012, to January 1, 2018) retrospective analysis of blood cultures from patients with suspected septicemia. Laboratory report data were used to determine patient demographic, bacterial profiles, and antimicrobial resistance patterns. A total of 2,404 blood cultures were processed during the study period. Data were analyzed using SPSS version 20 software and the results were summarized using tables and graphs.

RESULTS

Of the 2,404 blood cultures, 489 (20.7%, [95% CI, 19.2 - 22.3%]) bacteria isolates were obtained. The most common isolates were Staphylococcus aureus (215; 43.2%), followed by Klebsiella spp (67; 13.5%), coagulase-negative staphylococcus (62; 12.4%), Escherichia coli (38; 7.6%), viridans streptococci (25; 5%), Citrobacter spp (17; 3.4%), Enterobacter spp (15; 3%), and Streptococcus pneumoniae (12; 2.4%). Methicillin-resistant S. aureus isolation rate was 21/44 (47.7%). Gram-positive and negative bacteria showed high resistance to older antimicrobials, namely ampicillin, erythromycin, tetracycline, gentamicin, and trimethoprim-sulphamethoxazole. Gram-negative bacteria had a high level of resistance to 3rd generation cephalosporins, but both Gram-positive and negative bacteria were susceptible to ciprofloxacin.

CONCLUSIONS

S. aureus, CoNS, S. pneumoniae, Klebsiella spp and E. coli remain the most important bacteria responsible for bloodstream infection in this study. Those pathogens showed a high rate of resistance to old antibiotics. Among the tested antimicrobials, ciprofloxacin was found to be the most effective drug to inhibit the in-vitro growth of both Gram-positive and negative bacteria. Therefore, there is a need for continuous screening of AMR from blood cultures to control the spread of drug resistant isolates in the study area.

Antimicrobial resistance profile and multidrug resistance patterns of Streptococcus pneumoniae isolates from patients suspected of pneumococcal infections in Ethiopia

Background

Antimicrobial-resistant strains of Streptococcus pneumoniae have become one of the greatest challenges to global public health today and inappropriate use of antibiotics and high level of antibiotic use is probably the main factor driving the emergence of resistance worldwide. The aim of this study is, therefore, to assess the antimicrobial resistance profiles and multidrug resistance patterns of S. pneumoniae isolates from patients suspected of pneumococcal infections in Ethiopia.

Methods

A hospital-based prospective study was conducted from January 2018 to December 2019 at Addis Ababa city and Amhara National Region State Referral Hospitals. Antimicrobial resistance tests were performed from isolates of S. pneumoniae that were collected from pediatric and adult patients. Samples (cerebrospinal fluid, blood, sputum, eye discharge, ear discharge, and pleural and peritoneal fluids) from all collection sites were initially cultured on 5% sheep blood agar plates and incubated overnight at 37 °C in a 5% CO₂ atmosphere. Streptococcus pneumoniae was identified and confirmed by typical colony morphology, alpha-hemolysis, Gram staining, optochin susceptibility, and bile solubility test. Drug resistance testing was performed using the E-test method according to recommendations of the Clinical and Laboratory Standards Institute.

Results

Of the 57 isolates, 17.5% were fully resistant to penicillin. The corresponding value for both cefotaxime and ceftriaxone was 1.8%. Resistance rates to erythromycin, clindamycin, tetracycline, chloramphenicol and trimethoprim-sulfamethoxazole were 59.6%, 17.5%, 38.6%, 17.5 and 24.6%, respectively. Multidrug resistance (MDR) was seen in 33.3% isolates. The most common pattern was co-resistance to penicillin, erythromycin, clindamycin, and tetracycline.

Conclusions

Most S. pneumoniae isolates were susceptible to ceftriaxone and cefotaxime. Penicillin has been used as a drug of choice for treating S. pneumoniae infection. However, antimicrobial resistance including multidrug resistance was observed to several commonly used antibiotics including penicillin. Hence, it is important to periodically monitor the antimicrobial resistance patterns to select empirical treatments for better management of pneumococcal infection.

Multidrug resistance and extended-spectrum beta-lactamase producing Gram-negative bacteria from three Referral Hospitals of Amhara region, Ethiopia

Background

Multidrug resistance (MDR), extended-spectrum beta-lactamase (ESBL) and carbapenemase-producing Gram-negative bacteria (GNB) has become a public health threat worldwide. This threat is worse in developing countries where there is high infectious disease burden and spread of antimicrobial resistance co-exist. The aim of the present study was, therefore, to assess MDR, ESBL and carbapenemase producing GNB from patients attending three selected referral hospitals in Amhara region.

Methods

A cross-sectional study was conducted from December 2017- April 2018 at the University of Gondar Comprehensive Specialized Hospital, Dessie Referral Hospital and Debre Markos Referral Hospital of Amhara national regional state. A total of 833 study subjects were recruited using a convenient sampling technique. Clinical samples such as blood, urine, stool, wound, abscess, ear discharge, nasal discharge, cervical discharge and body fluid specimens were aseptically collected. Culturing for identification of bacteria and determination of drug susceptibility testing were done following standard microbiological techniques. Selected MDR isolates were phenotypically assessed for ESBL and carbapenemase production.

Results

Of the 833 clinical samples cultured for bacterial growth, 141 (16.9%) were positive for GNB. The most common GNB identified were E. coli 46 (32.6%), Klebsiella spp. 38 (26.5%) and Proteus spp. 13 (9.2%). The overall MDR prevalence was 121 (85.8%). Among the total isolates, 137 (97.2%) were resistant to ampicillin followed by cotrimoxazole 115 (81.6%), amoxicillin-clavulanic acid 109 (77.3%), cefixime 99 (70.2%), cefepime 93 (66.0%) and tetracycline 91 (64.5%). The extended-spectrum beta-lactamase producing GNB were 69/124 (55.6%). Of which Klebsiella spp. 19 (15.3%) and E. coli 17 (13.7%) were common ESBL producers. Carbapenemase-producing isolates were 8/51(15.7%). Of which Enterobacter, Klebsiella and E. coli were common carbapenemase producers.

Conclusion and recommendation

Multi-drug resistance and ESBL producing isolates in the present study were high. E. coli and Klebsiella spp. were the most common ESBL producing GNB. Klebsiella spp., Enterobacter spp., E. coli and Citrobacter spp. were typical carbapenemase-producing isolates. Continuous monitoring, antibiotic stewardship and molecular detection of the gene responsible for drug resistance are important means to reduce the spread of drug-resistant pathogens.

Production and characterization of biodiesel and glycerine pellet from macroalgae strain: Cladophora glomerata

Biodiesel was prepared by extracting oil from Cladophora glomerata green algae followed by transesterification of the oil using NaOH as a catalyst. The algae Oil extraction was carried out using two different techniques (Soxhlet and refluxing) and similar oil yield was obtained (23-24%). The resulting biodiesel showed desirable physical and chemical properties. Specific gravity, acid value, iodine value, ash content and calorific value of the algae biodiesel were within the specification of American Society for Testing and Materials (ASTM) and European Standards (EN). The analysis of fatty acid methyl ester composition revealed, 63, 27 and 10% for 9-octadecodenoic, hexadeconic and octadeconoic acid methyl ester, respectively. From the production line, two waste streams (glycerol and residual biomass) were combined to form a glycerine pellet. The measured energy content of the glycerine pellet was found to be comparable with firewood. Therefore, C. glomerata could potentially be utilized for the production of both biodiesel and glycerine pellet with no net waste in the transesterification process.                     KEY WORDS: Algae oil, Biodiesel, Transesterification, Glycerine pellet, Macroalgae, Cladophora glomerata   Bull. Chem. Soc. Ethiop. 2020, 34(2), 249-258 DOI: https://dx.doi.org/10.4314/bcse.v34i2.4

Prevalence of enteric bacteria and their antimicrobial susceptibility patterns among food handlers in Gondar town, Northwest Ethiopia

Background

Enteric bacterial pathogens are the major causes of food-borne gastroenteritis in humans and remain important public health problems worldwide. The emergence of antimicrobial resistance is a global concern, particularly in developing countries. The aim of this study was to determine the prevalence of enteric bacteria pathogens and their antimicrobial susceptibility patterns among food handlers in Gondar town, Northwest Ethiopia.

Methods

A cross-sectional study was conducted from February 4 to April 16, 2018. A total of 257 food handlers were selected using a multistage sampling technique. Data on socio-demographic characteristics were collected using a structured questionnaire. Stool samples were collected and inoculated into appropriate media. Enteric bacterial pathogens were identified using standard microbiological methods. Antimicrobial susceptibility tests were performed using the disk diffusion technique as per the standard Kirby-Bauer method. Data were entered and analyzed using SPSS version 20 software.

Results

The overall prevalence of enteric bacteria was 34/257 (13. 2%, [95% CI, 8.9-17.5%]). Shigella species was the leading isolate that accounted for 26/257 (10.1%) followed by Enterohemorrhagic Escherichia coli (EHEC) O157: H7 5/257 (1.9%) and Salmonella species 3/257 (1.2%). Shigella spp. was susceptible to ciprofloxacin 26 (100%), ceftriaxone 25 (96.1%), chloramphenicol 24 (92.3%), nalidixic acid 24 (92.3%), and gentamicin 20 (76.9%). Escherichia coli O157: H7 and Salmonella spp. showed the maximum (100%) susceptibility results to ceftriaxone, chloramphenicol, ciprofloxacin, and gentamicin. The overall prevalence of Multidrug resistance (MDR) in the current study was 14/34 (41.2%).

Conclusion

Our study showed high prevalence of enteric bacterial pathogens among food handlers. All isolates were susceptible to ciprofloxacin. However, a substential number of isolates were resistant to commonly prescribed antibiotics and the prevalence of MDR was high.

Bacterial profile and antimicrobial susceptibility patterns in chronic suppurative otitis media at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia

Objectives

This study aims to determine bacterial profile and antimicrobial susceptibility patterns of chronic suppurative otitis media in the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia.

Result

Sixty-two ear swabs were collected and 74 bacterial isolates were identified, of which 48 (77.4%) sample with mono-microbial growth, 11 (17.8%) with polymicrobial growth and the remaining 3 (4.8%) show no growth. The most common isolates were Proteus mirabilis 16 (21.6%), followed by S. aureus 12 (16.2%), Klebsiella spp. 10 (13.5%) and Providencia spp. 11 (14.9%). Proteus mirabilis was 100% susceptible to norfloxacin and ciprofloxacin while 87.5% of the isolates were susceptible to cefixime and gentamicin. S. aureus was 83.3% susceptible to gentamicin and clarithromycin, while 75% of the isolates were susceptible to amoxicillin–clavulanic acid and chloramphenicol, however, 66.7% the isolates were susceptible to ciprofloxacin, norfloxacin and erythromycin. The overall prevalence of multidrug resistance in the current study was 35 (47.3%). In this study P. mirabilis, S. aureus, Providencia spp., and Klebsiella spp. were the most common bacterial isolate and all Gram negative isolates were susceptible to ciprofloxacin and norfloxacin. Amoxicillin–clavulanic acid, gentamicin, chloramphenicol, clarithromycin and tobramycin were relatively effective against Gram positive bacteria.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4452-4) contains supplementary material, which is available to authorized users.

High prevalence of extended-spectrum beta-lactamase-producing Gram-negative pathogens from patients attending Felege Hiwot Comprehensive Specialized Hospital, Bahir Dar, Amhara region

Background

Infections caused by extended-spectrum beta-lactamases (ESBL) producing Gram-negative bacteria has emerge as a global threat in clinical practices. The treat is more serious in developing countries due to inappropriate use, poor adherence, use of counterfeit, sub-standard antibiotics and poor infection control practices. Data on ESBL producing Gram-negative bacteria are limited in developing countries including Ethiopia. The aim of this study was therefore, to describe the burden of ESBL producing Gram negative pathogens isolated from patients attending at Felege Hiwot Comprehensive Specialized Hospital, Bahir Dar, Amhara region.

Materials and methods

A total of 532 clinical samples of blood, urine, stool, wound, abscess, ear discharge, nasal discharge, cervical discharge and body fluid specimens were aseptically collected and bacteriologically processed. Identification of the bacterial species was performed using an automated system (Vitek-2 Compact 27530, USA) and antibiotic susceptibility test was determined by disk diffusion method and selection of antibiotics were in accordance with CLSI guidelines. The MDR pattern of the Gram-negative pathogens was assessed using phenotypic methods of ESBL and carbapenemase production following standard procedure.

Result

A total of 532 samples were processed and 263 pathogens were isolated. Of these, 185 (70.3%) were Gram-negative and 78 (29.7%) Gram-positive. Of the Gram-negative bacteria the high proportion of the isolates were identified from blood 146/185 (78.9%) and 29/185 (15.7%) were from urine cultures. The most common isolate in all clinical samples was Klebsiella pneumoniae 97/185 (52.4%) followed by Escherichia coli 23/185 (12.4%), Acinetobacter baumannii 15/185 (17.6%) and Enterobacter aerogenes 12/185(6.5%). Of the total Gram negatives, the prevalence of MDR was 148/185 (80.0%). Of the MDR isolates the prevalence of ESBL producers were, 127/148 (85.8%) and 24/148 (16.2%) were carbapenemase producers.

Conclusion and recommendation

Prevalence of MDR and ESBL producing Gram-negative pathogens in this hospital is alarmingly high. Therefore, continuous monitoring of the problem with effective infection prevention and careful selection of empirical therapy are warranted in the study area.

Multidrug-resistant bacterial isolates from patients suspected of nosocomial infections at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia

Objectives

As the hospital environment favors the circulation of drug resistant bacteria, continuous surveillance of antibiotic resistant patterns is an important approach for a better patient management. This study is therefore, aimed to assess multidrug resistant bacterial isolates from patients suspected of nosocomial infections at the University of Gondar Comprehensive Specialized Hospital, Gondar, Ethiopia.

Results

Of the 260 patients, 173 (66.5%) of them were culture positive. Among culture positive patients a total of 216 bacterial isolates were recovered, of which the most common species were S. aureus 77 (35.6%), followed by E. coli 33 (15.3%) and Klebsiella spp 29 (13.4%). Of the S. aureus isolates, 67.5% were cefoxitin (methicillin) resistant. Citrobacter spp (100%), Klebsiella spp (79.3%) and E. coli (75.3%) were the leading MDR Gram-negative isolates. The overall MDR resistant rate was 152 (70.4%).

Prevalence and antibiotic susceptibility patterns of Shigella and Salmonella among children aged below five years with Diarrhoea attending Nigist Eleni Mohammed memorial hospital, South Ethiopia

BACKGROUND

Diarrhoeal disease is the second leading cause of death among children aged below 5 years. Even though, both preventable and treatable diseases, globally there are nearly 1.7 billion cases of childhood diarrhoeal disease and responsible for killing around 525,000 children every year. Shigella and Salmonella species were the leading cause of etiologic agents for diarrhoea associated deaths. The aim of this study was to determine the prevalence and antibiotic susceptibility patterns of Shigella and Salmonella isolated from children aged below 5 years with diarrhoea attending Nigist Eleni Mohammed Memorial Hospital, Hossana, South Ethiopia.

METHODS

A cross sectional study was conducted from June 02 to September 24, 2017. Two hundred four children aged below 5 years with diarrhoea were enrolled consecutively using convenience sampling technique. Stool specimens were processed in accordance with the standard bacteriological methods and antibiotic susceptibility pattern of the isolates was determined using disc diffusion method. Data were analyzed using SPSS version 20.

RESULTS

Out of the 204 children aged below 5 years with diarrhoeal disease 19/204 (9.3%, [95%CI, 5.7-13.7%]) of them were positive for bacterial growth, of which 17/204(8.3%) were Shigella species and 2/204(1%) were Salmonella species. Both Shigella and Salmonella isolates were 100% susceptible to norfloxacin, nalidixic acid and kanamycin. However, isolates of Shigella showed 100, 76.5 and 64.7% resistance to ampicillin, gentamicin and cotrimoxazole respectively while Salmonella species were highly resistant to ampicillin and gentamicin (100% each).

CONCLUSIONS

Salmonella and Shigella species is prevalent in the current study area. Among the tested antibiotics, norfloxacin, nalidixic acid and kanamycin were found to be most effective for both isolates. Both species are developing resistance to the commonly prescribed antibiotic. Therefore, culture based bacterial species identification and antimicrobial susceptibility testing services are strongly recommended to avoid empirical treatment in the study area.

Tuberculosis along the continuum of HIV care in a cohort of adolescents living with HIV in Ethiopia

SETTING

Eight health facilities in Ethiopia.

OBJECTIVE

To determine tuberculosis (TB) incidence rates and associated factors among adolescents living with the human immunodeficiency virus (ALHIV).

DESIGN

This was a retrospective cohort study. Adolescents enrolled in HIV care between January 2005 and 31 December 2013 constituted the study population. The main outcome variable was TB diagnosis during follow-up. Baseline World Health Organization (WHO) clinical stage, CD4 count, previous history of TB and use of isoniazid preventive therapy (IPT) were the main independent variables. We estimated TB incidence rates as incident cases per 100 person-years of observation (PYO). Cox regression analysis was used to control for confounders.

RESULTS

Of the 1221 adolescents screened, 1072 were studied; 60.1% were girls. TB incidence rate was 16.32 per 100 PYO during pre-antiretroviral therapy (pre-ART) follow-up but declined to 2.25 per 100 PYO after initiation of ART. Advanced WHO clinical stage (adjusted hazard ratio [aHR] 2.71, 95%CI 1.69-4.33) and CD4 count <350 cells/μl (aHR 2.28, 95%CI 1.10-4.81) predicted TB incidence in the pre-ART cohort. IPT use was associated with a significant reduction in TB incidence in the ART cohort, but not in the pre-ART group.

CONCLUSION

Although TB was a significant problem in ALHIV, timely administration of ART and IPT had a significant protective effect.

Isolation of enterococci, their antimicrobial susceptibility patterns and associated factors among patients attending at the University of Gondar Teaching Hospital

Background

Enterococci become clinically important especially in immune compromised patients and important causes of nosocomial infections. Data on the prevalence, antimicrobial susceptibility patterns and associated factors of enterococci are scarce in Ethiopia.

Methods

A hospital based cross-sectional study was conducted at the University of Gondar Teaching Hospital from February 28, 2014 to May 1, 2014. Pretested structured questionnaire was used to collect socio-demographic data and possible associated factors of enterococci infections. Clinical samples including urine, blood, wound swabs and other body fluids from patients requested by physician for culture and antimicrobial susceptibility test during the study period were included. A total of 385 patients were included in the study. Data were entered and analyzed using SPSS Version 20. P values <0.05 were considered as statistically significant.

Result

The overall prevalence of enterococci infection was 6.2% (24/385). The commonest sites of infections were urinary tract followed by wound and blood. Among the 24 isolates, 33.3% (8/24) were resistant to all tested antimicrobial agents. Forty one point 7 % (10/24) of the enterococci isolates were vancomycin resistant enterococci (VRE). Moreover, two third of the isolates were multidrug resistant (MDR) enterococci. In multivariate analysis, duration of hospital stay for two days and more than two days with infection rate 17/32 (53.1%), previous history of any antibiotics (AOR = 9.13; [95% CI; 2.01–41.51] P = 0.00) and history of urinary catheterization (AOR = 8.80; [95% CI; 1.70–45.64] P = 0.01) were associated with presence of higher enterococci infections than their respective groups.

Conclusion

The prevalence of enterococci infections among patients with UTIs, wound infections and sepsis were higher than the other infections. Multi drug resistant enterococci including VRE were isolated from clinical samples in the study area. Being hospitalized for ≥48 h, having history of any antibiotic administration and catheterization were associated factors for enterococci infections. Presence of VRE indicates decreased antibiotic treatment options of multidrug resistant enterococci. Therefore, efforts should be made to prevent enterococci infections and emergency of multidrug resistant enterococci. Moreover, species identification and antibiotic resistant in advanced and at large scale is demanding.

Prevalence of vancomycin resistant Enterococci and associated risk factors among clients with and without HIV in Northwest Ethiopia: a cross-sectional study

Background

Enterococci are the most important multidrug resistant organisms associated with immunocompromised patients. Data are lacking about the epidemiology of vancomycin resistant Enterococci (VRE) in Ethiopia. This study aimed to assess the prevalence of VRE, their susceptibility patterns to different antibiotics and associated risk factors in fecal samples of Human Immunodeficiency Virus (HIV) positive and HIV negative clients.

Methods

A cross sectional study was carried out in a total of 226 (113 HIV positive and 113 HIV negative) clients, from July 1/2013 to September 30/2013 at the University of Gondar Teaching Hospital. Data on socio-demographic characteristics and risk factors were collected with a short interview guided by pre-tested structured questionnaire. The enterococci were isolated and identified from stool sample using standard bacteriological procedures. Kary Bauer disk diffusion method was used to determine the susceptibility patterns of Enterococci isolates. Data were entered and analyzed using SPSS version 20 statistical package.

Results

The overall colonization of Enterococci was 88.9% (201/226) of which 11 (5.5%) were VRE. The prevalence of VRE among clients with and without HIV infections were 8(7.8%) and 3(3.1%), respectively. Ninety percent of the Enterococci isolates (181/201) were resistant to two or more antibiotics tested. Isolates of Enterococci recovered from stool samples of HIV infected patients were more resistant to amoxicillin and amoxicillin-calvulinic acid than HIV negative clients (P < 0.05). Antibiotic treatment for the last 2 weeks was found to be the risk factor that showed statistically significant association with the presence of high VRE colonization. However, the socio-demographic variables and factors such as malnutrition, leucopenia, thromobocytopenia, anaemia, duration of Highly Active Antiretroviral Therapy, CD4 cell count, stage of WHO and drinking alcohol were not associated with VRE (P > 0.05).

Conclusion

The high prevalence of VRE in this study signals the emergence of VRE in the study area. Prior antibiotic treatment was associated with VRE colonization. Therefore, rational use of antibiotics and more detailed study using phenotypic and genotypic methods are needed.

Herbal medication: potential for adverse interactions with analgesic drugs

The use of herbal supplements in the US has increased dramatically in recent years. These products are not regulated by the Food and Drug Administration (FDA) with the same scrutiny as conventional drugs. Patients who use herbal supplements often do so in conjunction with conventional drugs. This article is a review of potential adverse interactions between some of the commonly used herbal supplements and analgesic drugs. Non-steroidal anti-inflammatory drugs (NSAIDs), particularly aspirin, have the potential to interact with herbal supplements that are known to possess antiplatelet activity (ginkgo, garlic, ginger, bilberry, dong quai, feverfew, ginseng, turmeric, meadowsweet and willow), with those containing coumarin (chamomile, motherworth, horse chestnut, fenugreek and red clover) and with tamarind, enhancing the risk of bleeding. Acetaminophen may also interact with ginkgo and possibly with at least some of the above herbs to increase the risk of bleeding. Further, the incidences of hepatotoxicity and nephrotoxicity may be augmented by acetaminophen when concomitantly used with the potentially hepatotoxic herbs Echinacea and kava, and with herbs containing salicylate (willow, meadowsweet), respectively. The concomitant use of opioid analgesics with the sedative herbal supplements, valerian, kava and chamomile, may lead to increased central nervous system (CNS) depression. The analgesic effect of opioids may also be inhibited by ginseng. It is suggested that health-care professionals should be more aware of the potential adverse interactions between herbal supplements and analgesic drugs, and take appropriate precautionary measures to avoid their possible occurrences. However, as most of the interaction information available is based on individual case reports, animal studies and in vitro data, further research is needed to confirm and assess the clinical significance of these potential interactions.

Cardiovascular responses of the taurine-depleted rat to vasoactive agents

The objective of this study was to assess the effect of taurine-depletion on cardiovascular responses of rat to vasoactive agents. Male Wistar-Kyoto (WKY) rats were given either tap water (control) or 3% beta-alanine (taurine-depleted) for three weeks. Thereafter, mean arterial pressure (MAP) and heart rate of the freely moving animal were measured in response to vasoactive agents. Administration of phenylephine (5-40 microg/kg/min; i.v.) resulted in a similar and significant increase in MAP but a reduction in heart rate in both control and taurine-depleted groups. On the other hand, administration of sodium nitroprusside (15-300 microg/kg/min; i.v.) elicited a similar and significant reduction in MAP but increased heart rate in both groups. Lack of a differential response to phenylephrine and sodium nitroprusside between the two groups suggests that baroreflex regulation of cardiovascular function is not adversely affected by taurine-depletion. Administration of angiotensin II (0.1-3.0 microg/kg/min; i.v.) resulted in a dose-related increase in the pressor response and a decrease in heart rate in both groups. However, angiotensin II-induced pressor response was reduced in the taurine-depleted compared to the control rats (p < 0.05); heart rate was similarly reduced in both groups. Acute exposure to beta-alanine (3 g/kg; i.v., 30-minutes) did not alter angiotensin II-induced hemodynamic responses. Similarly, incubation of aortic rings with beta-alanine (40mM, 30 minutes) did not affect the contractile responses to angiotensin II. The results suggest that beta-alanine, per se, does not affect angiotensin II-induced responses in rat. However, beta-alanine-induced taurine depletion is associated with a reduction in the pressor response to angiotensin II without impairing baroreflex function.

Effects of chronic taurine treatment on reactivity of the rat aorta

The effects of chronic taurine treatment on the reactivity of the aorta form male Wistar-Kyoto rats were investigated. Contractile responses to norepinephrine (NE) and potassium chloride (KCl) were attenuated in aortic rings from taurine-treated rats as compared to controls both in the absence and presence of endothelium. However, the degree of attenuation was greater in endothelium-intact tissues contracted with NE. Acetylcholine (Ach)-induced relaxation responses were augmented in endothelium-intact vessels from rats supplemented with taurine compared to the responses observed in control preparations. Relaxation responses of the aortae from control and taurine-treated rats to sodium nitroprusside (SNP) were not different from each other. Our results suggest that taurine treatment attenuates vascular contractility nonspecifically and this effect is partly mediated via the endothelium.

Renal adenosine A3 receptors in the rat: assessment of functional role

The functional roles of adenosine A3 receptors in the rat kidney were assessed for the first time with respect to A1 receptor-mediated responses. Utilizing a chronically instrumented conscious rat preparation, we tested renal excretory responses to acute administration of the A3 receptor antagonists 3-ethyl-5-benzyl-2-methyl-6-phenyl-4-phenylethynyl-1 ,4-(+)-dihydropridine-3,5-dicarboxylate (MRS-1191) and 9-chloro-2-(2-furyl)-5-phenylacetylamino-[1,2,4]-triazolo[1,5-c]qu inazoline (MRS-1220) with reference to the effects of the A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX). The intravenous administration of DPCPX resulted in significant increases in fluid and sodium excretions without affecting glomerular filtration rate (GFR). This suggests that DPCPX-induced diuretic and natriuretic responses are related to decreased tubular reabsorption. However, neither MRS-1191 nor MRS-1220 alone affected fluid or sodium excretions, or GFR, indicating lack of an effect of either compound on renal function. On the other hand, the co-administration of MRS-1220 with DPCPX abolished both the diuretic and natriuretic responses to DPCPX, being suggestive of antagonism between these two compounds. MRS-1191, however, did not affect the DPCPX-induced fluid and sodium excretions. Neither the A1 nor the A3 receptor antagonists altered potassium excretion individually or in combination. The data suggest that while adenosine A1 receptors are involved in the regulation of renal fluid and sodium transport, A3 receptors do not appear to have a major role in regulation of renal excretory function under baseline physiological conditions.

Antagonism of coronary artery relaxation by adenosine A2A-receptor antagonist ZM241385

We have tested the existence of functional A2A adenosine receptor in porcine coronary artery using, for the first time, the new A2A antagonist ZM241385. Nonselective agonist NECA and A2A-selective agonist CGS21680 produced concentration-dependent relaxation of prostaglandin F2alpha (PGF2alpha)-precontracted endothelium intact (E+) and denuded (E-) rings. Relaxation was significantly greater in E+ rings than in E-rings. A2A adenosine receptor-selective antagonist, ZM241385 (10(-6) M), significantly attenuated the relaxation responses. The antagonism of ZM241385 was compared with that of SCH58261 (10(-6)M), another A2A adenosine receptor-selective antagonist, which also significantly attenuated the relaxation response to both agonists. However, ZM241385 produced a significantly greater shift of the relaxation-response curves to the right compared with SCH58261 both in E+ and E- rings. The data show for the first time that ZM241385 is a potent A2A-receptor antagonist in porcine coronary artery and a useful tool to study A2A-receptor function.

A1 adenosine receptor-mediated Ins(1,4,5)P3 generation in allergic rabbit airway smooth muscle

The signal transduction pathway for A1 adenosine receptor in airway smooth muscle from allergic rabbits was studied by investigating the effect of the selective A1 adenosine-receptor agonist N6-cyclopentyladenosine (CPA) on tissue levels of inositol 1,4, 5-trisphosphate [Ins(1,4,5)P3] measured by protein binding assay. CPA caused a rapid, transient, and concentration-dependent elevation of Ins(1,4,5)P3 in airways from allergic rabbits. The agonist also produced a concentration-dependent contraction of the airway preparations from these animals. Both the Ins(1,4,5)P3 and contractile responses generated by CPA were attenuated by the phospholipase C (PLC) inhibitor U-73122, indicating the coupling of these responses to PLC. The CPA-induced Ins(1,4,5)P3 production observed in the allergic rabbit tissues was also inhibited by the adenosine-receptor antagonist 8-( p-sulfophenyl)-theophylline, suggesting that the effect was mediated by A1 adenosine receptors. On the other hand, the A2 adenosine-receptor agonist CGS-21680 was ineffective in altering the tissue concentration of Ins(1,4,5)P3, indicating that A2 adenosine receptors may not be involved in the activation of PLC in the allergic rabbit airway smooth muscle. In this preparation, the Gi-Go inhibitor pertussis toxin (PTX) attenuated the CPA-induced Ins(1,4,5)P3 accumulation, providing evidence that the generation of Ins(1,4,5)P3 by A1 adenosine-receptor stimulation is coupled to a PTX-sensitive G protein(s). The results suggest that activation of A1 adenosine receptors in allergic rabbit airway smooth muscle causes the production of Ins(1,4,5)P3 via a PTX-sensitive G protein-coupled PLC, and this signaling mechanism may be involved, at least in part, in the generation of contractile responses. It is hypothesized that this process may contribute to adenosine-induced bronchoconstriction in allergic asthma.

Effect of low density lipoprotein on adenosine receptor-mediated coronary vasorelaxation in vitro

We investigated the effect of low density lipoprotein (LDL) on vasorelaxations and nitric oxide generation induced by the adenosine analogs, 5'-(N-ethylcarboxamide)adenosine, 2-p-(2-carboxyethyl)phenylethyl-amino-5'N-ethylcarboxamidoadenosine and/or 2-chloroadenosine in porcine coronary artery rings in vitro. Preincubation of tissues with native LDL (100 and 200 microg/ml) for 4 hr in the absence or presence of copper sulfate (5 microM) selectively attenuated the endothelium-dependent relaxations elicited by 5'-(N-ethylcarboxamide)adenosine and 2-p-(2-carboxyethyl)phenylethyl-amino-5'N-ethylcarboxamideoadenosine+ ++ without altering the response to 2-chloroadenosine which produced endothelium-independent relaxation. The 4-hr exposure of tissues to native LDL (100 microg/ml) also inhibited the production of nitrite induced by 5'-(N-ethylcarboxamide)adenosine in endothelium-intact rings. These effects were associated with enhanced oxidation of the lipoprotein. The inhibitory action of LDL on tissue relaxations and nitrite generation as well as the oxidation of the lipoprotein were all prevented by high density lipoprotein (100 microg/ml). In contrast, a relatively short period (20 min) of tissue incubation with native LDL produced no alterations of the relaxations and nitrite production evoked by 5'-(N-ethylcarboxamide)adenosine and 2-p-(2-carboxyethyl)phenylethyl-amino-5'N-ethylcarboxamidoadenosine. Under this condition, the oxidation of LDL was not also significantly altered. In conclusion, the results indicate that in coronary artery LDL, with oxidative modification, causes attenuation of nitric oxide-mediated endothelial responses induced by adenosine receptors activation, and this effect is prevented by high density lipoprotein. Such modulation may be of importance in hypercholesterolemia and in the development of atherosclerosis.

Functional and morphological evaluation of canine veins following preservation in different storage media

Injuries of endothelial and smooth muscle cells of autologous vein due to preservation in standard storage media may be responsible for graft failure. The effects of vein preservation with University of Wisconsin solution (UWs) on endothelial and smooth muscle cell function and morphology were compared to the effects of preservation with autologous whole blood (AWB) and normal saline (NS), which are frequently used in cardiovascular surgery. Canine external jugular and common femoral vein segments were preserved in the different solutions at 4 degrees C for 45 min and 24 hr. Rings (4-5 mm in length) from control and preserved veins were evaluated by isometric tension studies at 37 degrees C and by scanning and transmission electron microscopy. Differences between groups were evaluated by Student's t test or Mann-Whitney U test and by analysis of the variance, and considered to be significant at P < 0.05. Sensitivities to norepinephrine (NE) showed that a 45-min vein storage in AWB (5.7 +/- 0.2 mumol/L) but not in NS (5.8 +/- 0.2 mumol/L) or UWs (6.5 +/- 0.2 mumol/L) had a deleterious effect on function of smooth muscle (P < 0.05) when compared to control veins (6.6 +/- 0.2 mumol/L). Maximum contractile responses and sensitivities to NE were significantly altered (P < 0.05) after 24-hr vein storage in AWB (0.09 +/- 0.02 g/mm2 and 5.4 +/- 0.07 mumol/L) and NS (0.12 +/- 0.03 g/mm2 and 5.6 +/- 0.08 mumol/L) but not in UWs (0.36 +/- 0.06 g/mm2 and 6.4 +/- 0.07 mumol/L). With both storage times, acetylcholine-induced endothelium-dependent maximum relaxations and sensitivities were significantly reduced (P < 0.05) in veins stored in AWB and NS, but not in UWs, compared with controls. Similarly, transmission electron microscopy revealed marked neutrophil migration beneath the intimal surface of vessels and extensive separation and desquamation of endothelial cells with exposure of subendothelial structures in veins stored in AWB and NS. The results suggest that UWs is a suitable storage medium when compared to AWB and NS.

Short-term preservation of autogenous vein grafts: effectiveness of University of Wisconsin solution

BACKGROUND

Suboptimal preservation of autologous veins in storage solutions causes endothelial cell damage that can contribute to graft failure. The purpose of this study was to compare the effects of short-term storage of veins in autologous whole blood (AWB), 0.9% normal saline solution (NS), and University of Wisconsin solution (UWs) on vein structure and function after grafting.

METHODS

Autogenous jugular and femoral veins were atraumatically harvested from mongrel dogs. One vein segment was immediately implanted to serve as a control, and the other segments were stored for 45 minutes in AWB, NS, or UWs. The veins were implanted as reversed interposition graft in the carotid or femoral arteries. After 6 weeks light and scanning electron microscopy and isometric tension studies were performed on explanted vein grafts.

RESULTS

Morphologic studies revealed an intact endothelium that stained positively for factor VIII. Intimal thickness was similar between controls (48 +/- 12 microns) and veins stored in UWs (53 +/- 8 microns) (p = not significant), but it was significantly increased in veins stored in AWB (151 +/- 29 microns) and NS (149 +/- 18 microns) (p < 0.05). Sensitivity and maximum contraction to norepinephrine were not altered in veins preserved in UWs (6.0 +/- 0.1 mumol/L and 0.19 +/- 0.02 gm/mm2) but were significantly reduced (p < 0.05) in those stored in AWB (7.2 +/- 0.1 mumol/L and 0.08 +/- 0.02 gm/mm2) and NS (7.0 +/- 0.3 mumol/L and 0.09 +/- 0.02 gm/mm2) compared with controls (5.9 +/- 0.2 mumol/L and 0.20 +/- 0.02 gm/mm2). The sensitivity and maximum relaxation to acetylcholine and sodium nitroprusside of veins preserved in AWB, NS, and UWs were similar to controls (p = not significant).

CONCLUSIONS

Vein storage in UWs preserves smooth muscle cell function compared with veins stored in NS or AWB. Therefore UWs is a more suitable medium for short-term preservation of veins in cardiovascular operation.

Enhanced contractile responses of arteries from streptozotocin diabetic rats to sodium fluoride

1. Previous studies from this laboratory have demonstrated that alpha 1-adrenoceptor-mediated increases in tension and phosphoinositide metabolism are enhanced in the aorta and mesenteric arteries from diabetic rats. The purpose of the present investigation was to determine whether contractile responses to sodium fluoride (NaF), which directly stimulates GTP-binding proteins (G-proteins), are also enhanced in diabetic arteries. 2. NaF (1-20 mM) in the presence of 10 microM aluminium chloride produced slowly developing, concentration-dependent contractions in mesenteric arteries from three month streptozotocin-diabetic (60 mg kg-1, i.v.) male Wistar rats and age-matched control rats. The maximum contractile response but not the sensitivity to NaF was significantly greater in mesenteric arteries from diabetic than from control rats, as was the response to noradrenaline (NA). Maximum contractile responses of aorta and caudal artery from diabetic rats to NaF were also significantly enhanced. 3. Removal of the endothelium and denervation with 6-hydroxydopamine did not significantly alter the maximum contractile response of mesenteric arteries from either control or diabetic rats to NaF. Similarly, NaF had no effect on cyclic AMP levels in aorta, and no difference in cyclic AMP levels, either basally or in the presence of NaF, was detected between control and diabetic rat aorta. 4. Contractile responses of mesenteric arteries from both control and diabetic rats to NaF were diminished in calcium-free Krebs solution, but the NaF response remained significantly elevated in mesenteric arteries from diabetic rats compared to control. 5. Ryanodine (30 microM) which depletes intracellular calcium stores, nifedipine (3 microM) which blocks dihydropyridine-sensitive calcium channels and calphostin C (0.5 microM) which selectively inhibits protein kinase C, all significantly inhibited maximum contractile responses of mesenteric arteries from control and diabetic rats to NaF. There were no significant differences between control and diabetic arteries in the relative magnitude of the inhibition produce by the three antagonist. 6. These data suggest that there may be increased activation of the same signalling processes that mediate NA-stimulated vasoconstriction, perhaps contraction-associated G-proteins or the effectors coupled to these G-proteins, in response to NaF in mesenteric arteries from diabetic rats. This may also be responsible for the enhanced contractile responses of these arteries to alpha 1-adrenoceptor stimulation.

G-proteins in guinea pig airway smooth muscle: identification and functional involvement

In airway smooth muscle, G-proteins have not been identified directly as yet. This study was an attempt to detect various types of conventional Gi- and Gs-proteins in purified membranes of guinea pig airway smooth muscle and to assess the involvement of the G-proteins in agonist-induced contractile response of the smooth muscle. Immunoblotting using AS/7 antibody which recognizes Gi-1/2 demonstrated the presence of polypeptides of M(r) 34, 41 and 75 kDa. Polypeptides of M(r) 43, 46 and 48 kDa were identified with RM/1 antibody that detects Gs-type G-proteins. The AG/1 antibody that recognizes alpha-subunits common to all Gi- and Gs-proteins detected two polypeptides of M(r) 41 and 75 kDa. Heterotrimeric structure of the G-proteins was confirmed by the identification of a single dense beta-subunit band at M(r) 39 kDa with SW/1 antibody. Pertussis toxin (PT) ADP-ribosylated three Gi alpha polypeptides of M(r) 41, 43, and 62 kDa. On the other hand, cholera toxin (CT) catalysed the ADP-ribosylation of two Gs alpha polypeptides of M(r) 46 and 62 kDa. Both PT and CT attenuated the maximum contractile responses of the airway smooth muscle to the muscarinic agonist, methacholine. Pretreatment of the tissues with the sulphydryl alkylating G-protein inhibitor, N-ethylmaleimide, also inhibited the maximum contractions to methacholine. These data suggest that plasma membranes of guinea pig airway smooth muscle contain a variety of conventional, including Gs and Gi, and other types of G-proteins, and at least a portion of the proteins present may be involved in mediating the contractile responses of the smooth muscle to an agonist such as methacholine.

Platelet-activating factor-induced inositol 1,4,5-trisphosphate generation in undifferentiated and differentiated U937 cells: role of tyrosine kinase

We compared the effect of platelet-activating factor (PAF) on inositol 1,4,5-trisphosphate (IP3) content in undifferentiated and differentiated U937 cells. In both cell types, PAF induced a rapid transient and concentration-dependent elevation of IP3 content. The production of IP3 in response to PAF was greater in differentiated than in undifferentiated cells. The increases in IP3 produced by PAF in both types of cell were inhibited by the PAF receptor antagonist, WEB 2086, as well as by the tyrosine kinase inhibitor, genistein. PAF also caused increased tyrosine phosphorylation of a 32 kDa protein substrate in both undifferentiated and differentiated cells. The magnitude of the phosphorylation was, however, greater in the differentiated cells. Genistein reduced the PAF-induced tyrosine phosphorylation of the substrate in both cell preparations. The specific binding of [3H]PAF was also markedly enhanced in differentiated cells. This effect was attenuated by genistein. The results indicate that PAF induces the production of IP3 in U937 cells via tyrosine kinase-mediated mechanisms and this process is augmented in differentiated cells.

Identification of guanine nucleotide binding regulatory proteins in bovine tracheal smooth muscle

The identity of G-proteins in airway smooth muscle is not well elucidated. In the present study, by immunoblotting using AS/7 antibody specific for Gi alpha-1/2, EC/2 antibody specific for Gi alpha-3 and RM/1 antibody specific for Gs alpha, we identified, respectively, Mr 39, 41, 46 and 52 KDa, Mr 41 and 43 KDa, and Mr 43 and 46 KDa polypeptides of conventional (heterotrimeric) G-proteins in purified membranes of bovine tracheal smooth muscle. The identity of the Mr 41, 43 and 52 KDa Gi alpha, and the Mr 43 and 46 Gs alpha was also confirmed by ADP-ribosylation with pertussis and cholera toxins, respectively. In addition, the common antibody (AG/1) for both Gi alpha and Gs alpha revealed the presence of all the above polypeptides, except the Mr 52 KDa band. By nitrocellulose blot overlay with [35S]s alpha GTP gamma S, we also detected seven low molecular weight GTP-binding proteins of Mr 18-30 KDa in the bovine tracheal smooth muscle. Photoaffinity crosslinking of [alpha-32P]GTP demonstrated the presence of high molecular GTP-binding proteins of Mr 55, 75 and 110 KDa. It is concluded that plasma membranes of bovine tracheal smooth muscle contain various types of conventional, low molecular weight and high molecular weight G-proteins. This warrantes further attention to elucidate the functional roles of G-proteins in airway smooth muscle.

Simultaneous measurement of intracellular calcium and tension in vascular smooth muscle: validation of the everted ring preparation

This study details and validates a method that facilitates the eversion of vascular smooth muscle, a preparation employed in in vitro Ca2+ fluorometric assays. Vascular segments of porcine coronary artery, approximately 2 cm in length, were sutured to portions of polyethylene tubing inserted into the lumen of the vessel. After being secured and stabilized by the tubing, the vessel was easily everted while immersed in physiological buffer. Intracellular calcium concentrations ([Ca2+]i) and tension were measured simultaneously in everted rings denuded of the endothelium. In these preparations, increases in tension generated by KCl and prostaglandin F2 alpha (PGF2 alpha) were accompanied by increases in [Ca2+]i, as measured by fura-2 fluorescence. Isoproterenol (ISO) and sodium nitroprusside (SNP) elicited reductions in muscle tension as well as [Ca2+]i in both KCl- and PGF2 alpha-contracted rings. Comparison of the responsiveness of everted and uneverted coronary artery rings demonstrated that, while fura-2 fluorescence in uneverted rings was negligible, the magnitudes of contraction of both preparations to KCl or PGF2 alpha were similar. The relaxant responses to ISO and SNP were also similar in the everted and uneverted rings contracted with KCl or PGF2 alpha. The data suggest that the procedure employed in everting vascular segments maintains the integrity of the smooth muscle, thus making it a suitable model for the simultaneous measurement of [Ca2+]i and tension.

Role of nitric oxide in adenosine receptor-mediated relaxation of porcine coronary artery

In the present study, using porcine coronary artery rings in vitro, we examined the role of the nitric oxide (NO) pathway in endothelium-dependent vasorelaxant effects of the 5'-uronamide adenosine agonists, 5'-(N-ethylcarboxamido)adenosine (NECA) and 2-[p-(2-carboxyethyl)]phenylethyl-amino-5'-N-ethylcarboxamidoadenosine (CGS-21680) as opposed to the endothelium-independent actions of the C2- and N6-substituted analogues, 2-chloroadenosine (CAD) and N6-cyclopentyladenosine (CPA). The NO synthase inhibitor, NG-monomethyl-L-arginine (L-NMMA, 30 microM), and the NO-destroying agent, 6-anilino-5,8-quinolinedione (LY-83583, 10 microM), attenuated the relaxations of endothelium-intact but not -denuded rings to NECA and CGS-21680. The effect of L-NMMA on NECA-induced relaxation was reversed by L-arginine (100 microM), a substrate for NO synthesis. In the endothelium-intact tissues, both NECA and CGS-21680 elicited enhanced production of nitrite, a stable metabolite of NO. This was also attenuated by L-NMMA or endothelium removal. Furthermore, NECA (10 microM) induced augmentation of guanosine 3',5'-cyclic monophosphate (cGMP) production in the intact arteries, which was also inhibited by L-NMMA, LY-83583, or endothelium removal. In contrast, vasorelaxant responses generated by CAD and CPA were not altered by either L-NMMA or LY-83583. Both agents (10 microM) were also unable to alter nitrite and/or guanosine 3',5'-cyclic monophosphate (cGMP) levels of the coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

University of Wisconsin solution effects on intimal proliferation in canine autogenous vein grafts

This study was carried out to investigate if the University of Wisconsin solution (UWs) is suitable for long-term preservation of autogenous vein grafts (AVG) prior to transplantation, compared to autologous whole blood (AWB) and normal saline (NS). Autogenous jugular and femoral veins were harvested from adult mongrel dogs, using a "no-touch" technique. One segment of vein was immediately implanted to serve as a control, while other segments were stored for 24 hr at 4 degrees C in AWB, NS, or UWs. The control and the preserved veins were implanted as reversed interposition grafts in the common carotid or femoral artery positions. After 6 weeks, scanning electron microscopy revealed an intact endothelial cell monolayer in all vein grafts that was stained positively for factor VIII. The degree of intimal thickening, as assessed by light microscopy in the middle position of the grafts, was similar in controls (52.0 +/- 15.8 microns) and in veins stored in UWs (58.5 +/- 16.1 microns), but it was significantly increased (P < 0.05) in veins preserved in NS (198.9 +/- 19.5 microns) and in AWB (312.0 +/- 171.6 microns). Isometric tension studies revealed that maximum contraction and sensitivities (assessed by EC50) to norepinephrine were significantly reduced (P < 0.05) in AVG stored in AWB (0.05 +/- 0.02 g/mm2 and 5.5 +/- 2.8 microM), but not in UWs (0.16 +/- 0.03 g/mm2 0.92 +/- 0.34 microM) and NS (0.09 +/- 0.03 g/mm2 and 3.0 +/- 1.1 microM), compared with controls (0.17 +/- 0.03 g/mm2 and 0.99 +/- 0.38 microM). Acetylcholine (Ach)-induced maximum relaxations were similar in all of the veins.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of tyrosine kinases in norepinephrine-induced contraction of vascular smooth muscle

We used various probes to examine the involvement of tyrosine kinases in norepinephrine (NE)-induced contractile responses of the isolated rat aorta denuded of endothelium. The putative tyrosine kinase inhibitors, genistein and tyrphostin, significantly inhibited the contractile responses of the aorta to NE but not to potassium chloride (KCl). The protein tyrosine phosphatase inhibitor, sodium orthovanadate, also selectively potentiated the contractile response of the artery to NE. The inhibitory effect of genistein on NE-induced contraction was observed both in the absence and presence of extracellular calcium, which produced phasic and tonic contractile responses, respectively. The effect of genistein was more pronounced on the phasic contraction, suggesting that tyrosine kinases play a greater role in mediating the responses associated with the release of intracellular calcium. Genistein, however, had no effect on contraction elicited by the direct protein kinase C (PKC) activator phorbol 12, 13 dibutyrate (PDB), providing evidence for the lack of involvement of tyrosine kinases in PKC-mediated contractile responses which contribute to the NE-induced tonic contraction. In contrast, genistein attenuated the contraction of the vessel evoked by the direct G-protein activator sodium fluoride (NaF), suggesting the involvement of tyrosine kinases in responses associated with G-protein activation. The data indicate that genistein- and tyrphostin-sensitive tyrosine kinases participate in NE-induced contraction of rat aortic smooth muscle. Although this may involve one or more steps in the signal transduction pathway, the enzymes appear to have a greater role in mediating the responses linked to the release of intracellular calcium and have no roles in certain other processes, including those mediated by PKC activation.

G-proteins in rat blood vessels--I. Identification

1. The purpose of this investigation was to identify various types of conventional, low and high molecular weight G-proteins in purified membranes of rat aorta and mesenteric artery. 2. In both blood vessels, immunoblotting of G-proteins using AS/7 antibody specific for Gi-1/2, EC/2 antibody specific for Gi-3 and RM/1 antibody specific for Gs-type conventional G-proteins demonstrated the presence of M(r) 28-43 kDa, M(r) 41 and 48 kDa, and M(r) 36-46 kDa polypeptides, respectively. Immunoblotting using a common antibody (GA/1) for the Gs and Gi alpha-subunits also revealed the existence of multiple polypeptides (M(r) 24-52 kDa) in both aorta and mesenteric artery, some of which were identified by the specific antibodies. The intensity and number of bands detected by most of the antibodies were greater in mesenteric artery than in aorta. 3. Cholera toxin (CT) catalyzed ADP-ribosylation of two Gs alpha (M(r) 43, 46 kDa) in both types of blood vessels with similar intensities of bands. Pertussis toxin (PT), on the other hand, catalyzed ADP-ribosylation of one Gi alpha (M(r) 41 kDa) polypeptide, and the intensity of this band was greater in aorta than in mesenteric artery. The polypeptides ADP-ribosylated by the toxins corresponded with their identification by antibodies. 4. Nitrocellulose blot overlay with [35S]GTP gamma S identified at least seven low molecular weight G-proteins (M(r) 21-30 kDa) in both aorta and mesenteric artery, with greater intensity of bands in mesenteric artery.(ABSTRACT TRUNCATED AT 250 WORDS)

G-proteins in rat blood vessels--II. Assessment of functional involvement

1. In this study, we compared G-protein-mediated contractile responses of rat aorta and mesenteric artery rings induced by the alpha-adrenoceptor agonist, norepinephrine (NE) and by the direct G-protein activator, sodium fluoride, using various probes. 2. Activator of the stimulatory G-protein (Gs), cholera toxin (CT), attenuated the sensitivity and maximum contractile response of both aorta and mesenteric artery to NE and sodium fluoride. The effect of the toxin on the NE-sensitivity was greater in mesenteric artery. 3. Pretreatment of tissues with the inhibitor of Gi-protein, pertussis toxin (PT), reduced the sensitivity as well as maximum contraction of both the aorta and mesenteric artery to sodium fluoride, and of the mesenteric artery to NE. PT attenuated only the sensitivity but not the maximum contraction of the aorta to NE. The inhibitory effect of PT on sensitivity to NE or sodium fluoride was greater in the aorta. 4. NE and sodium fluoride-induced contractions were reduced by the sulfhydryl G-protein inhibitor, N-ethylmaleimide (NEM) in both blood vessels. NEM produced greater inhibitory effect on the sensitivity of the aorta to both contractile agents. 5. These data demonstrate that CT, PT and NEM-sensitive G-proteins are involved in NE- and sodium fluoride-induced contractile responses of the rat aorta and mesenteric artery. The differential effects of the G-protein probes indicate that certain variations in G-protein-mediated contractile responses exist among the two blood vessels, suggesting that G-protein involvement in functional responses may vary with the type of blood vessel investigated.

Role of extracellular Ca2+ in the selective enhancement of contractile responses of arteries from diabetic rats to noradrenaline

Maximum contractile responses of diabetic aortas incubated in the absence of extracellular Ca2+ to increasing Ca2+ (0.01-10 mM) in the presence of 1 microM noradrenaline, but not 40 mM KCl, were significantly increased compared with those of age-matched control rats. Maximum contractile responses of both aortas and mesenteric arteries from diabetic rats to noradrenaline, but not KCl, in the presence of extracellular Ca2+ (2.5 mM) were also significantly enhanced. The Ca2+ channel antagonists verapamil and nifedipine and the Ca2+ channel agonist BAY K8644 produced a similar percentage change in the magnitude of the noradrenaline response in arteries from both control and diabetic rats. These data confirm the selective nature of the enhancement of contractile responses of arteries from diabetic rats to noradrenaline and suggest that this may be mediated in part through enhanced noradrenaline-induced influx of extracellular Ca2+ through channels sensitive to the Ca2+ channel ligands. However, this does not appear to be the only explanation for the enhanced contractile responses of diabetic arteries to noradrenaline, since in the presence of maximum concentrations of nifedipine (3 microM) and verapamil (10 microM), responses of diabetic arteries to noradrenaline were still greater than those of control arteries.

Adenosine receptor-mediated relaxation of porcine coronary artery in presence and absence of endothelium

This study was designed to investigate the effects of a series of adenosine analogues on porcine coronary artery in vitro. In both endothelium-intact and -denuded rings, 5'-(N-ethylcarboxamido) adenosine (NECA), 2-[p-(2-carboxyethyl)]phenylethylamino-5'-N-ethylcarboxamidoadenos ine (CGS-21680), 2-chloroadenosine (CAD), N6-R-phenylisopropyladenosine (R-PIA), 2-phenylaminoadenosine (PAA), N6-cyclohexyladenosine (CHA), N6-cyclopentyladenosine (CPA), and N6-S-phenylisopropyladenosine (S-PIA) produced concentration-dependent relaxations. The rank order of potency was consistent with A2-adenosine receptor identification. The xanthine adenosine antagonist, 8-(sulfophenyl) theophylline (8-SPT), attenuated the relaxant responses to all the agonists in the endothelium-intact rings and to only CAD, R-PIA, PAA, CHA, CPA, and S-PIA in the denuded preparations. Except for NECA and CGS-21680, the slopes of the relaxation curves and the dissociation constant (Kb) values for 8-SPT were similar for all agonists. In addition, endothelium removal selectively reduced the responses to NECA and CGS-21680. The adenosine receptor agonist, CGS-22988, also relaxed the denuded rings in a manner insensitive to blockade by 8-SPT. The data suggest that multiple A2-adenosine receptors exist on the smooth muscle and endothelium of porcine coronary artery, mediating relaxation. Whereas the smooth muscle contains both xanthine-sensitive and -insensitive A2-receptors, which can be activated by a wide range of adenosine agonists, the endothelium possesses xanthine-sensitive receptors that can be stimulated selectively by certain adenosine agonists, including 5'-uronamide derivatives, such as NECA and CGS-21680. The smooth muscle also appears to contain xanthine-insensitive A4-receptors activated by CGS-22988.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional and morphological assessment of rat aorta stored in University of Wisconsin and Eurocollins solutions

University of Wisconsin (UW) and Eurocollins (EC) solutions are widely used for preservation of organs before transplantation. However, effect of storage solutions on vascular interface for transplant success is not known. In this study, we have used rat aorta as a model and assessed the effects of cold storage in UW and EC solutions on smooth muscle and endothelial function and the morphology. Smooth muscle and endothelial functions of the rat aorta were assessed using in vitro isometric tension measurement. Morphologic studies were done with scanning and transmission electron microscopy. No significant difference in contractile response to either norepinephrine (NE) or potassium chloride was observed between control aorta and aorta stored in UW solution for 1 hr or 24 hr. In contrast, sensitivity, but not the reactivity to NE and KCl, was increased in aorta stored in EC solution for 1 hr. If the tissues were stored in EC solution for 24 hr, both sensitivity and reactivity to NE and KCl were significantly reduced. Relaxatory response to acetylcholine, in endothelium-intact vessels were reduced in aortas stored in EC solution, but not in UW solution. The magnitude of relaxations observed in tissues stored in the EC solution for 24 hr was less than in tissues stored for 1 hr. Sodium nitroprusside elicited similar relaxatory response in endothelium-denuded control tissue and in tissues stored in UW and EC solution. Electron microscopy data revealed marked swelling of the cell, loss of mitochondria and other intracellular organelles, and striking calcium deposits after preservation of the vessels in EC for 1 or 24 hr. In aorta stored in UW solution for 24 hr, endothelial and smooth muscle cells were intact, with moderate-size vacuoles in the cytoplasm. These results suggest that the UW solution is more suitable than EC solution for short-term preoperative storage of blood vessels.

Augmented inositol phosphate production in mesenteric arteries from diabetic rats

The effects of noradrenaline (NA) on contraction and phosphoinositide metabolism were compared in mesenteric arteries from rats with chronic streptozotocin-induced diabetes and from age-matched control rats. Maximum contractile responses of mesenteric arteries from diabetic rats to NA (30 microM) were significantly greater than control in both the presence and absence of extracellular Ca2+. Basal incorporation of [3H]myoinositol into total [3H]inositol phosphates was greater in diabetic than control mesenteric arteries. NA (30 microM) resulted in a time-dependent increase in total [3H]inositol phosphate production, which was also significantly greater in diabetic than in control preparations. The increase in total [3H]inositol phosphates produced by NA in both control and diabetic arteries was blocked by the alpha 1-adrenoceptor antagonist, prazosin. Absolute levels of inositol 1,4,5-trisphosphate (I(1,4,5)P3), measured by protein binding assay, were also increased in response to 30 microM NA in both control and diabetic arteries. Although basal I(1,4,5)P3 levels were not significantly different, NA-induced increases in I(1,4,5)P3 were significantly greater in diabetic than in control arteries at each time-point measured. These data indicate that phosphoinositide metabolism is enhanced in mesenteric arteries from rats with chronic streptozotocin-induced diabetes in response to a maximum concentration of NA. Augmented production of the second messengers I(1,4,5)P3 and, presumably, 1,2-diacylglycerol may contribute to the enhanced maximum contractile responses of the diabetic arteries to NA.

Enhanced arterial contractility to noradrenaline in diabetic rats is associated with increased phosphoinositide metabolism

The purpose of this study was to investigate whether the increased contractile responsiveness of aortae from male rats with 12-14 week streptozotocin-induced diabetes to noradrenaline is associated with alterations in phosphoinositide metabolism. The contractile response to noradrenaline (10 microM) in both the presence and absence of extracellular calcium was significantly enhanced in aortae from diabetic rats. No significant differences were found between control and diabetic arteries in the basal incorporation of 32P and [3H]myo-inositol into phosphoinositides, or in the basal accumulation of [32P]phosphatidic acid and [3H]inositol phosphates. However, noradrenaline (10 microM) caused significantly greater breakdown of [32P]phosphatidylinositol 4,5-bisphosphate and formation of [32P]phosphatidic acid and [3H]inositol phosphates in diabetic aortae than in control preparations. The production of [3H]inositol phosphates induced by noradrenaline was selectively reduced by the alpha 1-adrenoceptor antagonist, prazosin, in both control and diabetic tissues. These results indicate that phosphoinositide metabolism in response to noradrenaline via stimulation of alpha 1-adrenoceptors is enhanced in aortae from chronic streptozotocin-diabetic rats. The increase in inositol 1,4,5-trisphosphate and 1,2-diacylglycerol production that presumably results could be responsible, at least in part, for the enhanced contractile response of aortae from diabetic rats to noradrenaline.

Influence of diabetes on norepinephrine-induced inositol 1,4,5-trisphosphate levels in rat aorta

The effects of norepinephrine on total tissue levels of inositol 1,4,5-trisphosphate were measured by protein binding assay in aortas from rats with chronic streptozotocin-induced diabetes and from age-matched control rats. In both control and diabetic aortas, norepinephrine induced a rapid, transient and concentration-dependent elevation of inositol 1,4,5-trisphosphate content during contraction. Maximum production of inositol 1,4,5-trisphosphate in response to norepinephrine was greater in diabetic than in control aortas. However, the sensitivities of control and diabetic aortas to norepinephrine for inositol 1,4,5-trisphosphate production were not significantly different. Enhanced norepinephrine-induced production of inositol 1,4,5-trisphosphate in diabetic aortas may contribute to the increased maximum contractile responsiveness of these arteries to the agonist. However, since enhanced contractile responses of diabetic aortas to norepinephrine were also detected at times when inositol 1,4,5-trisphosphate levels were not significantly increased, other factors also appear to be involved in mediating enhanced contractions of diabetic arteries to norepinephrine.

Protein kinase C-mediated contractile responses of arteries from diabetic rats

1. The role of protein kinase C (PKC) in mediating enhanced contractile responses of aortae and mesenteric arteries from male rats with 12-14 week streptozotocin-induced diabetes to noradrenaline (NA) was investigated using the PKC activator, phorbol 12,13-dibutyrate (PDB), and the PKC inhibitor, staurosporine. 2. Maximum contractile responses of aortae and mesenteric arteries from diabetic rats to NA were significantly enhanced compared with responses of arteries from age-matched control animals. The maximum NA responses were increased by 59.6 +/- 7.9% in aortae and by 54.9 +/- 7.4% in mesenteric arteries from diabetic animals, compared to their respective controls. 3. Pretreatment of aortae and mesenteric arteries from both control and diabetic animals with staurosporine (5 x 10(-8) M) caused marked inhibition of contractile responses to a maximum concentration of NA (10(-5) M in aortae; 3 x 10(-5) M in mesenteric arteries). In the presence of staurosporine, no difference was observed in the magnitude of contractile responses of arteries from control and diabetic rats to NA. 4. Maximum contractile responses of mesenteric arteries from diabetic rats to PDB were significantly increased (by 45.0 +/- 4.9%) compared to responses of arteries from control animals. In contrast, no significant difference was found in the magnitude of contractile responses or aortae from control and diabetic rats to PDB. 5. Staurosporine (5 x 10(-8) M caused marked attenuation of contractile responses of arteries from control and diabetic rats to a maximum concentration of PDB (3 x 10(-6) M). In the presence of staurosporine, the difference in magnitude of contractile responses of mesenteric arteries from control and diabetic rats to PDB was abolished. 6. Contractile responses of aortae and mesenteric arteries from control and diabetic rats to PDB were reduced in the absence of extracellular Ca2", and in the presence of the Ca2 + channel blockers, nifedipine (3 x 10-6 M) or verapamil (3 x 10-6 M). Under these conditions, no difference was found in the magnitude of contractile responses of mesenteric arteries from control and diabetic rats to PDB. 7. These data suggest that enhanced contractile responses of aortae and mesenteric arteries from streptozotocin-induced diabetic rats to NA may result, at least in part, from increased activation of PKC. In addition, increased activation of PKC-mediated processes, which are dependent on the presence of extracellular Ca2+, may further contribute to the enhanced contractile responses of diabetic mesenteric arteries to NA.

Enhanced contractile responses of arteries from diabetic rats to alpha 1-adrenoceptor stimulation in the absence and presence of extracellular calcium

The purpose of this study was to determine the receptor subtype mediating enhanced contractile responses of aortae and mesenteric arteries from diabetic rats to the alpha-adrenoceptor agonists, norepinephrine, clonidine, and methoxamine and to establish whether the enhanced responses are associated with increased release of intracellular Ca2+ or are dependent on the presence of extracellular Ca2+. The pA2 values calculated for the alpha 1-selective antagonist prazosin were similar in arteries from control and diabetic rats and were 2.5-3 log units greater than pA2 values calculated for the alpha 2-selective antagonist yohimbine. Contractile responses of aortae incubated in Ca2(+)-free Krebs' solution containing 1 mM EGTA to maximal but not to ED50 concentrations of the alpha-adrenoceptor agonists were significantly greater in preparations from diabetic than from control rats. Following readdition of Ca2+, contractile responses of diabetic aortae to all concentrations of the agonists tested were significantly greater than control. Similar results were obtained in mesenteric arteries, except that no clonidine response could be detected in preparations from either diabetic or control rats in the absence of extracellular Ca2+. These data indicate that enhanced responses of arteries from diabetic rats to alpha-adrenoceptor agonists are mediated by alpha 1 adrenoceptors, and are largely dependent on the presence of extracellular Ca2+. However, increased release of intracellular Ca2+ appears to contribute to enhanced responses to high concentrations of these agonists.

Traditional pharmaceutical practice in Gondar region, northwestern Ethiopia

The knowledge and skills of Ethiopian traditional healers in Gondar region on the pharmaceutical aspects of their practice were assessed using a questionnaire. Of the 86 healers interviewed, only 83 gave responses good enough to be considered in the analysis of results. It was shown that the healers obtained their drugs mainly from natural substances and these in descending order of frequency were plants, animals and minerals. The healers prepared the drugs in various dosage forms including liquids, ointments, powders and pills. They also prescribed drugs in a "non-formulated" form. They usually incorporated additives and more than one drug in a single dosage form. Drugs were administered using eight routes, the main ones being, topical, oral and respiratory. Most of the healers claimed to determine doses and to know about side-effects of drugs. When side-effects became severe, "antidotes" were claimed to be used. The healers imposed restriction when certain types of drugs were taken by patients. Most of them stored the drugs that should not be dispensed immediately after collection or preparation. Drugs were usually stored in containers such as bottles, papers, pieces of cloth, leaves and horns, and were kept anywhere at home. The results are discussed mainly in relation to modern pharmaceutical and medical practices and their importance to health care services among the people in Gondar region is also stated.